Breathing masks configured to administer gases (e.g. aerosol or oxygen) to a patient have been available for many years. However, these prior art devices are not entirely acceptable for a variety of reasons.
For example, U.S. Pat. No. 6,659,102 to Sico, the entire disclosure of which is hereby incorporated herein by reference, discloses an oxygen mask filter system for preventing the transmission of disease. The mask has an inhalation valve and a plurality of vent apertures mounted on opposing sides of the mask. Filter members are removably mounted on each side of the mask. The filter members are mounted by a post member having a flanged end. Consequently, the filter system is comparatively complex and utilizes a multitude of moving parts. Moreover, the interchangeability of the mask with multiple filters is relatively limited.
Another mask assembly is described in U.S. Pat. No. 5,579,761 to Yuschak et al., the entire disclosure of which is also hereby incorporated herein by reference. This mask assembly includes a respirator having a face piece and a cartridge receiving structure located on the face piece. The mask assembly uses an inhalation filter. An exhalation filter is not positioned between a flange portion and a cover with an exhalation vent to reduce exposure of harmful agents to others that may be in the same room as the patient using the mask. Therefore, healthcare personnel administering treatments to patients are exposed to free airborne medication mist which potentially causes infectious diseases.
Yet another mask assembly includes a plurality of apertures on the face piece. A flexible valve disc covers the apertures to prevent any inhaled air from entering through the apertures. When a patient exhales, the air flows through the apertures, around the disc, and is airborne. Therefore, healthcare professionals and emergency personnel administering treatments to patients are exposed to airborne contaminated oxygen particles. In addition, should the nasal portion of the mask fail where the patient is inhaling pure oxygen, there is a chance of suffocation because the valve disc would block any air from passing from the environment through the apertures since the valve disc completely surrounds the apertures.
Accordingly, in order to address these disadvantages, there have been various additional attempts to provide mask assemblies to reduce the transfer of bacteria/viruses to or from an infected patient. Examples of mask assemblies are disclosed in U.S. Pat. No. 4,440,163 to Spergel; U.S. Pat. No. 4,934,361 to Michel et al.; U.S. Pat. No. 5,226,412 to Winters; U.S. Pat. No. 5,647,356 to Osendorf et al.; U.S. Pat. No. 6,298,849 to Scholey et al.; and U.S. Pat. No. 6,584,976 to Japuntich et al., and U.S. Patent Publication No. 2004/0084048 to Stenzler et al.; the disclosures of each are hereby incorporated herein by reference in their entirety. Although some of the features of those mask assemblies ease the disadvantages described above, a continuing need exists for an improved mask assembly which minimizes or eliminates release of patient exhaled gases and/or surplus medication into room air; is readily interchangeable with a number of different types of filters; is relatively simple to use, make, and assemble; and which simultaneously reduces the number of parts necessary for manufacture and assembly.